1. Field of the Invention
The present invention provides a light-tight cassette for holding a roll of photosensitive material. Examples of such material would be a roll of printing paper and a roll of photographic film. The cassette particularly is adaptable for use as it is provided with a pull tab arrangement at an opening of the cassette for loading the photosensitive material under sunlight or indoor illumination.
2. Description of the Prior Art
Various types of packages for photosensitive materials have been disclosed. Examples of these disclosures are Japanese Utility Model Unexamined Published Application (hereinafter referred to as "OPI") No. 88980/80; Japanese Utility Model Application No. 16608/81; Japanese Patent Application (OPI) No. 124140/80; Japanese Patent Application (OPI) No. 128333/82; U.S. Pat. Ser. No. 4,068,247; Japanese Patent Application (OPI) No. 156058/85; U.S. Pat. Ser. No. 4,148,395; U.S. Pat. Ser. No. 4,179,028 and U.S. Pat. Ser. No. 4,272,035.
FIG. 5 shows a light-tight cassette as disclosed in U.S. Pat. Ser. No. 4,068,247. Therein, a cassette 10 for holding a roll of a light-sensitive photographic material comprises a tubular body portion 1 and two end caps IA and IB. The web 3 of photographic material is pulled out of the roll through a slot-like opening 2 which extends between the two end caps. In the figure, the photographic material has been illustrated as being transparent. The slot 2 is provided with a construction of any well known type, for example, such as disclosed by U.S. Pat. Ser. No. 4,568,590 (hereinafter incorporated by reference) for preventing light from reaching the photosensitive web 3 in the cassette 10. The tubular body 1 is usually manufactured from a material such as plastic and/or cardboard. The tubular body 1 may be manufactured by an extrusion process or manufactured by bending a plastic sheet or a cardboard sheet into the appropriate shape.
The end caps may be made of a polyolefin such as polypropylene and polyethylene or polystyrene. During molding operations of the end caps, the ratio of contraction of the polyolefins, such as polypropylene and polyethylene, may be quite large. A frame which is part of the end cap extends along the total circumference or perimeter thereof and is subject to possible inward warpage when the end cap is formed as a rectangle by injection molding. This can cause problems of light leakage into the cassette when the end caps are assembled to the tubular body and which would then adversely effect the photosensitive material contained therein. Further, as previously discussed, due to the inward warps of the end caps, the accuracy and efficiency of the assembly of the containers is also adversely affected. For that reason, cassettes may be improperly assembled which could cause damage to the photosensitive material.
The cassettes identified in the foregoing prior art have a drawback in that it is difficult to make the bend or crease lines of the plastic sheet material or cardboard sheet material completely straight during the manufacturing process which transforms the plastic sheets or cardboard sheets into the tubular body forming the cassettes. The bending process of the plastic or cardboard sheets is predisposed to provide a tubular, polygonal body that is slightly rounded in form. When a photosensitive web is then subsequently packaged in the tubular body having the slightly rounded cross-section, it is difficult to fit the end caps to both ends of the body in order to seal off the photosensitive material from exposure to light. This is particularly true as the end caps may be fitted to both ends of the tubular body while in a darkroom as would be required to provide a complete cassette. Accordingly, the accuracy and efficiency of assembly-line work for manufacturing the cassette is significantly affected and, as a result, a large number of improperly assembled unfinished cassettes are likely to be manufactured.
In order to overcome the foregoing deficiencies of prior art photosensitive material cassettes, the present invention provides a container in which the end caps, serving to close the open ends of the substantially polygonal cross-section tubular body are provided with a unique construction. This construction provides the end caps with outer and inner frames extending along the total circumference of the end openings of the tubular body. The outer and inner frames are located at a substantially uniform distance from each other so that a groove is defined between the outer and inner frames. Edges of the corresponding open ends of the tubular body are engaged in the groove. When the end caps are in position to close off the corresponding ends of the tubular body, light is blocked from entering into the cassette. The outer frame of the end cap is provided with corner portions which project, toward the longitudinal direction of the tubular body to a greater extent than corner portions of the inner frame. Additionally, a corner portion of the outer frame is trimmed to a partial extent so that it will not contact and thus interfere with the photosensitive web that will be withdrawn through the outlet opening of the tubular body.
In order to overcome the problems associated with the foregoing discussions, one object of the present invention is to provide end caps for photosensitive material cassettes in which the end caps are made from polyolefins such a polypropylene and polyethylene or polystyrene. In order to facilitate assembly and prevent warpage of the end caps made from this material, the caps are provided with an outer frame and an inner frame and a plurality of ribs provided at regular intervals therebetween. The ribs or projections engage in notches provided in the tubular body.
Accordingly, it is an object of the present invention to solve the above-discussed drawbacks by providing a photosensitive material web cassette in which the positioning of end caps, to the tubular body, is simplified and permits the end caps to be assembled to the tubular body in an efficient manner, even when the assembly takes place in a darkroom.